This application is for renewal of a postdoctoral training grant that is focused primarily on sleep/circadian biology and sleep disorders, in particular sleep-disordered respiration. Sleep disorders are increasingly being recognized as extremely common disorders that have a significant morbidity and even mortality. Sleep apnea results in excessive daytime sleepiness and an increased risk of vehicular crashes; it is also associated with an increased risk of hypertension, stroke and myocardial infarction. Although sleep disorders are very common, there is limited knowledge about the basic mechanism of disease or about outcomes of therapy. This is largely related to the paucity of investigators in this area. That this is the case was recognized in the early: 1990s by the U.S. Congress, who established the National Center for Sleep Disorders Research. A National Research Plan for Sleep was developed by NIH; this plan spoke eloquently of the major need for investigators both in basic science, and in patient-oriented research related to sleep and its disorders. Currently, however, very few institutions have a critical mass of investigators in this area to mount a training program. There is, at the University of Pennsylvania (Penn), a large number of established investigators in different departments studying sleep and its disorders. These investigators are both in basic science and in patient-oriented research. They have collaborated and are collaborating in programs that include this training program and a Special Center of Research (SCOR) in Neurobiology of Sleep and Sleep Apnea. Thus, this group has the ability to mount a major training program to meet what is perceived to be a major national need. The training program, which is a three year program, has the following four major tracks: a) molecular biology/biochemistry; b) systems neurobiology; c) translational research; and d) clinical epidemiology. In each track fellows are given the opportunity to do relevant course work and some will pursue a Master's degree. Much of their research training is research conducted under a mentor. The program uses a group mentorship strategy with a mentorship committee put in place for each fellow to oversee the training program and provide advice to the trainee and primary mentor(s). The training program proposed takes advantages of many of the highly established academic entities and training mechanisms at Penn. The training program includes structures to help with grant writing and provides career counseling. There is an active minority recruitment program with minority investigators collaborating with the Program Director in this effort.